We examine multimode diode laser pump depletion in a graded index multimode (MM) fibre Raman laser generating a high-quality Stokes beam. Spatial ‘hole burning’ in the transmitted pump beam is demonstrated. A balance model is constructed for interaction of the pump and Stokes waves in the MM Raman laser. Analytical formulas are derived and used in calculations demonstrating qualitative agreement with experimental data. The origin of the observed quantitative discrepancies is discussed.

中文翻译：

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渐变折射率多模光纤中拉曼激光的泵浦耗尽

我们检查了梯度折射率多模 (MM) 光纤拉曼激光器中的多模二极管激光泵耗尽，该激光器产生高质量的斯托克斯光束。演示了透射泵浦光束中的空间“烧孔”。建立了一个平衡模型，用于 MM 拉曼激光器中泵浦和斯托克斯波的相互作用。分析公式被导出并用于计算，证明与实验数据的定性一致。讨论了观察到的数量差异的起源。